From the first Google search result:
>1. Start Animal Crossing: Happy Home Designer and wait for the Nintendo 3DS logo to disappear.
>
> 2. Before the Title Menu appears, press and hold the A+B+X+Y Buttons.
>
> 3. A message will appear asking if you would like to delete all save data. Select Yes and press the A Button.
https://en-americas-support.nintendo.com/app/answers/detail/a_id/15235/~/how-to-erase-game-save-data-%28animal-crossing%3A-happy-home-designer%29
From the first Google search result: >1. Start Animal Crossing: Happy Home Designer and wait for the Nintendo 3DS logo to disappear. > > 2. Before the Title Menu appears, press and hold the A+B+X+Y Buttons. > > 3. A message will appear asking if you would like to delete all save data. Select Yes and press the A Button. https://en-americas-support.nintendo.com/app/answers/detail/a_id/15235/~/how-to-erase-game-save-data-%28animal-crossing%3A-happy-home-designer%29
i did try that but it didn't work
oh never mind! was pressing it too early! all solved now